The invention relates to a display method and apparatus, and in particular, to a display method and apparatus capable of displaying component video signals conforming to various formats. Component video signals conforming to different formats are processed separately by corresponding application circuits, thus the display quality can be optimized.
Most conventional basic entry-level display apparatuses comprising component video signal inputs only support YCbCr (480i, 576i) formats, while higher level display apparatuses further support YPbPr (480p, 576p, 720p, 1080i) formats. Different component video signal formats, however, can not offer optimized video quality with only one application circuit. For example, to display a component video signal, a component video signal conforming to the YCbCr (480i, 576i) format is first decoded and converted to a digital video signal by a video decoder (e.g. Philips SAA7118 or Micronas VPC3230), and is then de-interlaced by a de-interlacer to obtain a progressive video signal (480p, 576p), which is then sent to a scaler IC to generate visual output. Currently, most of the video decoders and de-interlacers are capable of handling YCbCr (480i, 576i) formats, but unable to handle YPbPr (480p, 576p, 720p and 1080i) formats. To display component video signals conforming to YPbPr (480p, 576p, 720p, 1080i) formats, an analog-digital converter (ADC, e.g. Analog Device Inc. AD9883) is required to convert the component video signals into digital video signals, and a color space converter (CSC) is required to convert the color space of the digital video signal into RGB format before the scaler IC can generate visual output therefrom.
Circuits for processing YCbCr (480i, 576i) format component video signals are totally different from circuits for processing YPbPr (480p, 576p, 720p, 1080i) format component video signals. Additionally, conventional display apparatuses supporting multiple component video signal formats generally provide an on screen display (OSD) control for manually switching between YCbCr or YPbPr modes, which may be considered inconvenient. Some component video signal output terminals on DVD players are marked as conforming to YPbPr format, but actually output YCbCr (480i, 576i) format video signals, resulting in confusion when switching modes.
Some other display apparatuses supporting multiple component video signal formats route all video signals into the analog-digital converter and the color space converter, and then generate corresponding visual output through the scaler IC. This design reduces costs and design complexity, but sacrifices display quality for YCbCr (480i, 576i) format component video signals. As the obtained display quality for YCbCr component video signals is much worse than that obtained from a conventional video decoder and de-interlacer. For example, the anti-copying technology (i.e. Macrovision) in the video decoder is better than that in the analog-digital converter. Additionally, the video decoder is capable of providing saturation and tint adjustment, which is not provided by the analog-digital converter. Thus for YCbCr component video signals, the video decoder is more preferable.